Buggy code:
public class SignJar extends AbstractJarSignerTask { private static final FileUtils FILE_UTILS = FileUtils . getFileUtils ( ) ; protected String sigfile ; protected File signedjar ; protected boolean internalsf ; protected boolean sectionsonly ; private boolean preserveLastModified ; protected boolean lazy ; protected File destDir ; private FileNameMapper mapper ; protected String tsaurl ; protected String tsacert ; public static final String ERROR_TODIR_AND_SIGNEDJAR = "'destdir'<seq2seq4repair_space>and<seq2seq4repair_space>'signedjar'<seq2seq4repair_space>cannot<seq2seq4repair_space>both<seq2seq4repair_space>be<seq2seq4repair_space>set" ; public static final String ERROR_TOO_MANY_MAPPERS = "Too<seq2seq4repair_space>many<seq2seq4repair_space>mappers" ; public static final String ERROR_SIGNEDJAR_AND_FILESETS = "You<seq2seq4repair_space>cannot<seq2seq4repair_space>specify<seq2seq4repair_space>the<seq2seq4repair_space>signed<seq2seq4repair_space>JAR<seq2seq4repair_space>when<seq2seq4repair_space>using<seq2seq4repair_space>filesets" ; public static final String ERROR_BAD_MAP = "Cannot<seq2seq4repair_space>map<seq2seq4repair_space>source<seq2seq4repair_space>file<seq2seq4repair_space>to<seq2seq4repair_space>anything<seq2seq4repair_space>sensible:<seq2seq4repair_space>" ; public static final String ERROR_MAPPER_WITHOUT_DEST = "The<seq2seq4repair_space>destDir<seq2seq4repair_space>attribute<seq2seq4repair_space>is<seq2seq4repair_space>required<seq2seq4repair_space>if<seq2seq4repair_space>a<seq2seq4repair_space>mapper<seq2seq4repair_space>is<seq2seq4repair_space>set" ; public static final String ERROR_NO_ALIAS = "alias<seq2seq4repair_space>attribute<seq2seq4repair_space>must<seq2seq4repair_space>be<seq2seq4repair_space>set" ; public static final String ERROR_NO_STOREPASS = "storepass<seq2seq4repair_space>attribute<seq2seq4repair_space>must<seq2seq4repair_space>be<seq2seq4repair_space>set" ; public void setSigfile ( final String sigfile ) { } public void setSignedjar ( final File signedjar ) { } public void setInternalsf ( final boolean internalsf ) { } public void setSectionsonly ( final boolean sectionsonly ) { } public void setLazy ( final boolean lazy ) { } public void setDestDir ( File destDir ) { } public void add ( FileNameMapper newMapper ) { } public FileNameMapper getMapper ( ) { } public String getTsaurl ( ) { } public void setTsaurl ( String tsaurl ) { } public String getTsacert ( ) { } public void setTsacert ( String tsacert ) { } public void execute ( ) throws BuildException { } private void signOneJar ( File jarSource , File jarTarget ) throws BuildException { } private void addTimestampAuthorityCommands ( final ExecTask cmd ) { } protected boolean isUpToDate ( File jarFile , File signedjarFile ) { <START_BUG> if ( ( null == jarFile ) && ( ! ( jarFile . exists ( ) ) ) ) { <END_BUG> return false ; } File destFile = signedjarFile ; if ( destFile == null ) { destFile = jarFile ; } if ( jarFile . equals ( destFile ) ) { if ( lazy ) { return isSigned ( jarFile ) ; } return false ; } return SignJar . FILE_UTILS . isUpToDate ( jarFile , destFile ) ; } protected boolean isSigned ( File file ) { } public void setPreserveLastModified ( boolean preserveLastModified ) { } }

Fix:
if ( ( null == jarFile ) || ( ! ( jarFile . exists ( ) ) ) ) {